1. Field of the Invention
The present invention relates to a valve having relatively movable disk members each with a fluid opening which can be brought into and out of fluid conducting alignment for discharging fluid to a discharge port, and, more particularly, to improvements to such a valve which include means for centrally supporting the disk members in order to reduce the torque required to turn a first of the disk members relative to a second of the disk members at such times when the disk members are subjected to high fluid pressures.
2. Description of the Prior Art
This invention relates to a valve of the type having a stationary disk and a rotatable disk mounted in a valve housing in a face-to-face confronting relationship in a pathway for fluid in a valve body. The disks are each provided with at least one orifice or opening which controls the flow of fluid through the valve by the size of the openings in the disk as well as the degree of alignment between the openings in the disk. Angular movement of one disk relative to the other in the valve body is accomplished by moving or turning a handle situated outside of the valve body but coupled to produce rotation of the rotatable disk. The rotatable disk can be moved from a full open position wherein the opening or openings in one disk completely align with the opening or openings in the other disk for providing maximum flow through the valve to a fully closed position wherein the opening or openings in the respective disks are completely misaligned and blocked by solid portions of the confronting disks. Examples of valves which operate in this fashion are disclosed in U.S. Pat. No. 3,207,181, and in my prior U.S. Pat. Nos. and 4,901,977 and 5,054,521 as well as my copending U.S. patent applications Ser. Nos. 450,549 and 264,855 now U.S. Pat. No. 5,025,833 the disclosures of which are incorporated herein by reference.
Valves of this type are particularly useful for controlling the flow of fluids from oil and gas wells and the like. Such a valve is sometimes called a choke when used to control the rate of flow of well production fluids that may contain abrasive containments such as sand particles. The fluid entering the valve may be under extreme pressure on the order of, for example, 3000 PSI. The openings in the disks are of a smaller cross-sectional area than either an upstream entry chamber or a downstream discharge chamber that are formed in a valve body. The openings in the disks cause an acceleration of the fluid passing through the openings in the disk. Therefore, the fluid emerging from the opening in the downstream disk enters at an increased velocity a discharge chamber which has a cross-sectional area that is greater than the cross-sectional area of the openings in the disk, but because of the construction of the discharge chamber, particularly when provided with a replaceable protective sleeve or insert in the valve body, a large pressure drop in the fluid passing through the sleeve is created. The effect is to reduce the capacity of the valve, and, because of the construction of the removable sleeve, abrupt changes to the configuration of the opening in the sleeve produce turbulence in the fluid, particularly at the outlet of the valve which is unprotected by the removable sleeve.
In the known form of valves of the type under discussion such as disclosed in my U.S. Pat. No. 4,603,834, the outlet is defined by an oblong transverse configuration immediately downstream of the downstream disk. The oblong configuration is a result of the need to provide openings to receive retainer pins which are used to anchor the disk in the valve body. At times when a protective sleeve is required for the outlet chamber, the area of the oblong configuration is reduced by the thickness of the sleeve. The reduced oblong area of the outlet, in turn, limits the maximum size of the disk that can be use with the removable sleeve as compared with, for example, the size of the oblong outlet chamber when a removable sleeve is not used. The smaller volume for conducting fluid in the sleeve creates a larger pressure drop to the fluid passing through the sleeve, thus reducing the capacity of the valve.
Moreover, in the known form of valves using replaceable sleeves at the outlet chamber, the sleeve is adhered to the valve body by an adhesive, such as epoxy cement, which also is relied upon to prevent the flow of fluid between the sleeve and the valve body. When it is necessary to replace the sleeve, the valve body must be heated to a temperature sufficient to soften the epoxy so that the sleeve can be removed. Typically, it is known to heat a valve body to over 250 degrees Fahrenheit in order to effectively soften the epoxy for replacement of the sleeve.
An inherent and historic disadvantage of such multiple orifice valves is that when the disks are subject to extreme fluid pressures, the torque required to angularly move one disk relative to the other may sometimes be enormous. This problem is further compounded if the contacting faces of the stationary disk and the movable disk are polished or machined to a high level of surface finish quality. Moreover, at any given pressure, the torque required to turn one disk relative to the other is even further increased as the diameter of the disks increases.
An advantage exists, therefore, for a multiple orifice valve construction which requires relatively low torque in order to turn the movable disk relative to the stationary disk when the disks are subject to extreme fluid pressures. Such a construction should permit the aforesaid low turning torque regardless of the smoothness of the contacting faces of the disks and the diameter of the disks. Furthermore, such a construction should be equally advantageously used in the manufacture of new valves as well as in retrofitting existing valve assemblies.
It is therefore an object of the present invention to provide a multiple orifice valve construction including a stationary disk and an abutting movable disk wherein relatively low torque is required to angularly move the movable disk relative to the stationary disk even at such instances when the disks are subject to extreme fluid pressures.
It is a further object of the present invention to provide an multiple orifice valve construction wherein relatively low torque is required to turn the movable disk relative to the stationary disk even at such instances when the abutting faces of the disks are polished to an extremely high surface finish quality or smoothness.
It is a further object of the present invention to provide an multiple orifice valve construction wherein relatively low torque is required to turn the movable disk relative to the stationary disk regardless of the diameters of the disks.
It is a further object of the present invention to provide a improved construction of a sleeve member forming a discharge flow path for fluid emerging from the passageway in a disk member within a valve body to carry a seal to prevent flow of fluid about the outer periphery of the disk members as well as between the sleeve and support surfaces therefore in the valve body.
It is a further object of the present invention to provide a multiple orifice valve construction which is a advantageously used in the manufacture of new valves as well as in retrofitting existing valve assemblies.
Still other objects and advantages will become apparent in light of the attached drawings and written description of the invention presented hereinbelow.